Suffragan of Buenos Aires, in Argentine until recently, comprised two civil provinces, Entre Rios and Corrientes, and the civil Government of Misiones (see Map of South America in Vol. III). This territory belonged to the Diocese of Buenos Aires until 1854, when it became a separate pro-vicariate Apostolic, to be erected into a diocese by the Bull of Pius IX dated 13 June, 1859. The area of Entre Rios is 28,754 sq. miles; Corrientes, 32,545 sq. miles; Misiones, 8571 sq. miles. The respective populations are: Entre Rios, 408,000; Corrientes, 322,000; Misiones, 44,000. Thus the diocese has a total area of 69,870 sq. miles and a population of 774,000. The Diocese of Corrientes has recently been erected.

The first Bishop of Paraná, José Gabriel Segura y Cuvas, born at Catamarca, Argentine Republic, 1802; died 13 October, 1862, took possession of the see 3 June, 1860. His successor, José Mariá Gelabert y Crespo, born in 1820; died 23 November, 1897, took possession of the see 23 August, 1865, and was succeeded by Rosendo de la Lastra y Gordillo (died 3 July, 1909). The present bishop (1911), Abel Bazan y Bustos, born at La Rioja, 28 August, 1867, was preconized 7 February, 1910, consecrated 8 May, and took possession of the see 15 May, of the same year. The Province of Entre Rios is divided into sixteen parishes and ten chaplaincies (capellanías vicarias); Corrientes, forming one vicariate forain, twenty parishes; Misiones, one parish and three chaplaincies. The cathedral has a chapter of ten canons, including the five dignitaries. The "Guia Eclesiastica de Argentina" for 1910 gives the total number of clergy (parish priests and chaplains) for the diocese as 96; no mention, however, is here made of priests belonging to religious institutes engaged in educational work in the diocese. The conciliar seminary (Calle Urquiza, Paraná), under the direction of a rector, vice-rector, and five professors, has an aggregate of forty-three students in all its departments. The Benedictine Fathers have an agricultural school at Victoria, and the Capuchins conduct a college for boys at Concordia, both in Entre Rios. There are nine parochial schools in Entre Rios and one in Corrientes. Educational institutions for girls and charitable institutions of various kinds are conducted by the Daughters of the Immaculate Conception, the Religious of the Perpetual Adoration (Adoratrices), Servants of the Holy Spirit, Sisters of St. Francis, of St. Joseph (Lyons), and of the Garden, Vincentian Sisters, Belgian Tertiaries, Sisters of the Poor of St. Catherine of Siena, Carmelites (Tarragona), Mercedarians, and Tertiaries of Charity and of Carmel. Pious and charitable societies well represented in the diocese are the Acción Católica, the Apostleship of Prayer, the Confraternities (both for men and for women) of St. Vincent of Paul, Association for the Propagation of the Faith, Confraternities of Our Lady of Perpetual Succour and of Carmel, Daughters of Mary, and the peculiarly national Society of Our Lady of Itatí.

The Diocese of Corrientes also embraces Misiones. Rev. Luis A. Niella has been appointed bishop by the pope.